The invention relates to an arrangement for the production of straight-line or even symmetrical signals from at least two signal generators, which have a periodic structure and which are movable with respect to each other, by means of sensors that generate signals corresponding to the position of the signal generators.
Straight-line symmetrical signals are needed, for example, to ascertain the torque and torsion in rotating shafts. Gear wheels, marked wheels, rings, etc. already installed, or specially provided for this purpose, are generally used as the signal generators. The generation of signals is effected, for example, by magnetic sensors, such as Hall-effect devices, field plate sensors or, preferably, differential arrangements in which the difference of the external magnetic resistance at the poles of the sensor determines the sensor signal. In this arrangement, any particular sensor can only be used for one particular signal generator geometry with one particular periodic structure. Any deviation in the periodic structure, for example, in the tooth pitch in the case of gear wheels, will result in odd or skew-symmetrical signals which falsify the measurement result.
Federal Republic of Germany DE-OS No. 32 35 122 discloses a torque measuring instrument in which shifts or displacements of the shaft are compensated by the fact that four sensors are mounted in a horizontal plane on opposite sides of the shaft which is marked with patterns. In this arrangement, however, simultaneous symmetrization of the signals is not possible.